<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<HTML LANG="EN">
<HEAD>
<TITLE>VT100.net: Digital VT220 Programmer Reference Manual</TITLE>
<META NAME="DESCRIPTION" CONTENT="Digital VT220 Programmer Reference Manual, Chapter 1: Terminal Overview">
<LINK HREF="vt220-rm.css" TYPE="text/css" REL="STYLESHEET">
</HEAD>
<BODY>
<DIV CLASS="navbar"><A HREF="http://vt100.net/"><IMG CLASS="button" SRC="vt100.net-logo.png" ALT="VT100.net" HEIGHT="16" WIDTH="102"></A> VT220 Programmer Reference Manual<TABLE WIDTH="100%">
<COL SPAN="3" WIDTH="33%">
<TBODY>
<TR>
<TD ALIGN="LEFT"><A HREF="../../index.html">Preface</A></TD>
<TD ALIGN="CENTER"><A HREF="contents.html">Contents</A></TD>
<TD ALIGN="RIGHT"><A HREF="chapter2.html">Chapter 2</A></TD>
</TR>
</TBODY>
</TABLE>
<HR></DIV>
<H1 ID="S1">1 Terminal Overview</H1>
<H2 ID="S1.1">1.1 General</H2>
<P>This chapter provides an overview of the VT220 terminal. The
chapter describes the VT220's major features and operating modes.</P>
<P>The VT220 (<A HREF="figure1-1.html">Figure 1-1</A>) is a general-purpose, video display
terminal that uses ANSI standard functions. The terminal has two
major components, a monitor/system unit and keyboard.</P>
<H2 ID="S1.2">1.2 Terminal Features</H2>
<P>The following sections summarize the major VT220 features.</P>
<H3 ID="S1.2.1">1.2.1 Display Features</H3>
<P>The VT220 uses a monochrome monitor with the following features.</P>
<UL>
<LI><P>24 rows &times; 80/132 columns<BR>
7 &times; 10 dot matrix in a 10 &times; 10 cell for 80 columns<BR>
7 &times; 10 dot matrix in a 9 &times; 10 cell for 132 columns</P></LI>
<LI><P>800 (horizontal) &times; 240 (vertical) pixels (80 columns)<BR>
1188 (horizontal) &times; 240 (vertical) pixels (132 columns)</P></LI>
</UL>
<H3 ID="S1.2.2">1.2.2 Text Features</H3>
<P>This list summarizes the major VT220 text features.</P>
<UL>
<LI>Five character sets of 94 characters each (including the DEC multinational character set)</LI>
<LI>Down-line-loadable character set</LI>
<LI>User-definable function keys</LI>
<LI>Reverse video characters</LI>
<LI>Underline characters</LI>
<LI>Bold characters</LI>
<LI>Blinking characters</LI>
<LI>Double-height/double-width lines</LI>
<LI>ANSI-compatible control functions</LI>
<LI>VT52 mode</LI>
</UL>
<H2 ID="S1.3">1.3 Communication Environment</H2>
<P>The VT220 provides the following major communication features.</P>
<UL>
<LI>Asynchronous communications to 19.2 Kbits per second</LI>
<LI>EIA RS232C host port</LI>
<LI>20 mA host port</LI>
<LI>EIA RS232C printer port</LI>
<LI>7-bit and 8-bit character formats</LI>
</UL>
<H2 ID="S1.4">1.4 Operating States</H2>
<P>The VT220 has three operating states.</P>
<UL>
<LI>Set-up</LI>
<LI>On-line</LI>
<LI>Local</LI>
</UL>
<P><STRONG>Set-Up</STRONG><BR>The set-up state lets you select or examine terminal operating
features (such as transmit and receive speeds) from the keyboard.
You can also use set-up to select the on-line and local states. The
<CITE>VT220 Owner's Manual</CITE> describes set-up in detail.</P>
<P>You select set-up by pressing the <SPAN CLASS="keyname">Set-Up</SPAN> key.</P>
<P><STRONG>On-Line</STRONG><BR>The on-line state lets the terminal communicate with a host
computer. Data entered at the keyboard is sent to the host
computer. Data received from the host computer is displayed on the
monitor. You can also display data entered from the keyboard, if
you select the local echo feature in set-up or with a control
sequence.</P>
<P>You can only select on-line from set-up.</P>
<P><STRONG>Local</STRONG><BR>The local state lets you place the host computer on "hold". Data
entered at the keyboard is sent to the monitor, but not the host
computer. Data received from the host computer is stored; this
data is sent to the monitor after you put the terminal back
on-line.</P>
<P>You can only select local from set-up.</P>
<H2 ID="S1.5">1.5 Operating Modes</H2>
<P>The VT220 has four major operating modes. You can select these
modes from the keyboard, or from the host via control codes.</P>
<UL>
<LI>VT200 mode, 7-bit controls</LI>
<LI>VT200 mode, 8-bit controls</LI>
<LI>VT100 mode</LI>
<LI>VT52 mode</LI>
</UL>
<P><STRONG>VT200 mode, 7-bit controls</STRONG> is the default mode and executes
standard ANSI functions. This mode provides the full range of
VT220 capabilities in an 8-bit communications environment with
7-bit controls (<A HREF="chapter2.html">Chapter 2</A>). This mode supports the DEC
multinational character set or national replacement character
(NRC) sets, depending on the character set mode selected. You can
access both types of character sets from the keyboard, or from the
host computer via control codes. This operating mode also provides
some backward compatibility for existing VT100 software.</P>
<P><STRONG>VT200 mode, 8-bit controls</STRONG> executes standard ANSI functions. This
mode provides the full range of VT220 capabilities in an 8-bit
communications environment with 8-bit controls (<A HREF="chapter2.html">Chapter 2</A>). This
mode supports the DEC multinational character set or national
replacement character (NRC) sets, depending on the character set
mode selected. As in VT200 mode, 7-bit controls, you can access
both types of character sets from the keyboard or with programmed
control codes.</P>
<P><STRONG>VT100 mode</STRONG> executes standard ANSI functions. It has a high degree
of compatibility with Digital's VT102 terminal. (<A HREF="appendixa.html">Appendix A</A>
describes VT220/VT102 differences). This mode restricts use of the
keyboard to VT100 keys. All data is restricted to 7 bits, and only ASCII,
national replacement characters (NRC), or special graphics
characters are generated. This mode is provided for strict
backward compatibility with existing software written for the
VT100 terminal family.</P>
<P><STRONG>VT52 mode</STRONG> executes Digital (DEC) private functions (not ANSI). It
has a degree of compatibility with Digital's VT102 terminal
operating in a VT52 mode. This mode restricts use of the keyboard
to VT52 keys. All data is restricted to 7 bits, and only ASCII,
U.K., or special graphics characters are generated.</P>
<H2 ID="S1.6">1.6 Character Set Modes</H2>
<P>The VT220 has two character set modes, multinational and national.
You can select either mode from the keyboard in set-up, or from
the host computer via control codes.</P>
<P><STRONG>Multinational</STRONG> mode supports the DEC multinational character set
(DEC MCS). The DEC MCS is an 8-bit character set that contains
most characters used in the major European languages. The ASCII
character set is included in the DEC MCS.</P>
<P><STRONG>National</STRONG> mode supports the national replacement character sets
(NRC sets). The NRC sets are a group of eleven 7-bit character
sets. The national character set available is determined by the
keyboard selected in set-up. Only one national character set is
available for use at any one time. National mode restricts
compatibility to a 7-bit environment in which the use of the
DEC MCS is disabled.</P>
<DIV CLASS="navbar"><HR>
<TABLE WIDTH="100%">
<COL SPAN="3" WIDTH="33%">
<TBODY>
<TR>
<TD ALIGN="LEFT"><A HREF="../../index.html">Preface</A></TD>
<TD ALIGN="CENTER"><A HREF="contents.html">Contents</A></TD>
<TD ALIGN="RIGHT"><A HREF="chapter2.html">Chapter 2</A></TD>
</TR>
</TBODY>
</TABLE>
<DIV CLASS="navbot">http://vt100.net/docs/vt220-rm/chapter1.html</DIV></DIV>
</BODY>
</HTML>
